Warn if different media have the same name

Author: momchil-flex

tests/test_components/test_scene.py

@@ -47,7 +47,7 @@ def test_scene_init():
 
 
 def test_validate_components_none():
-    assert SCENE._validate_num_mediums(val=None) is None
+    assert SCENE._validate_mediums(val=None) is None
 
 
 def test_plot_eps():

tests/test_components/test_simulation.py

@@ -1715,6 +1715,27 @@ def test_num_mediums(monkeypatch):
         )
 
 
+def test_unique_medium_names():
+    """Warn if non-unique medium names supplied."""
+
+    with AssertLogLevel("WARNING", contains_str="unique names"):
+        _ = td.Simulation(
+            size=(5, 5, 5),
+            structures=[
+                td.Structure(
+                    geometry=td.Box(size=(1, 1, 1)),
+                    medium=td.Medium(permittivity=2, name="medium1"),
+                ),
+                td.Structure(
+                    geometry=td.Box(size=(1, 1, 1), center=(1, 0, 0)),
+                    medium=td.Medium(permittivity=3, name="medium1"),
+                ),
+            ],
+            run_time=1e-12,
+            grid_spec=td.GridSpec.uniform(dl=0.02),
+        )
+
+
 def test_num_sources():
     """Make sure we error if too many sources supplied."""
 

tidy3d/components/scene.py

@@ -142,8 +142,8 @@ class Scene(Tidy3dBaseModel):
     _unique_structure_names = assert_unique_names("structures")
 
     @pd.validator("structures", always=True)
-    def _validate_num_mediums(cls, val):
-        """Error if too many mediums present."""
+    def _validate_mediums(cls, val):
+        """Error if too many mediums present. Warn if different mediums have the same name."""
 
         if val is None:
             return val
@@ -155,6 +155,14 @@ def _validate_num_mediums(cls, val):
                 f"{len(mediums)} were supplied."
             )
 
+        medium_names = [medium.name for medium in mediums if medium.name is not None]
+        if len(medium_names) != len(set(medium_names)):
+            log.warning(
+                "Different mediums with the same name were detected. "
+                "This may error in future Tidy3D versions, and using unique names for distinct "
+                "media is recommended."
+            )
+
         return val
 
     @pd.validator("structures", always=True)